Espínter, Lucio Cornelio [Lucius Cornelius Lentulus Spinther] (s I a.C.)

Based on the theoretical models and rationale presented in Chapter 1, we aimed to test the presence of specific relations between measures of autonomic arousal, vigilance and alertness, visual attention, executive function and cognitive control, as following:

• Investigate the presence of any relations between measures of autonomic arousal, vigilance and alertness

• Investigate the presence of associations between indices of arousal and alertness, and visual attention mechanisms

• Investigate any relationships between indices of autonomic arousal, vigilance and alertness, and electrophysiological/behavioural measures of executive function and task performance

CSI and CVI have been proposed to be inversely related, so that higher CSI is usually an index of increased activation of the SNS and a predictor of reduced HRV, while CVI is likely to be an index of increased activation of the PNS and a predictor of higher HRV. In line with previous studies who supported this idea (e.g., see Bourdon et al., 2018; Oliveira, et al., 2019), we expected to find an inverse correlation between CSI and CVI, so that increased activity in one branch of the ANS (e.g., increased CSI) would be associated with reduced activity in the other branch (e.g., reduced CVI). We expected to find associations between HRV measures and alpha oscillations, so that increased alpha during the POP task might predict the presence of indices of reduced autonomic arousal, such as reduced CSI or increased CVI and RMSSD. Since the P3 is thought to specifically mirror activity of the LC-NE system, we investigated if higher P3a during the oddball task was associated with HRV measures collected during the same task.

We used a trial-by-trial approach to investigate the relation between baseline pupil size and SRTs during the gap-overlap task, to test if pupil size during fixation before an eye movement (index of tonic arousal and vigilance) could predict the latency of a saccade after the presentation of the peripheral stimulus, and if this differed in relation to the presence of ADHD and ASD. We also investigated the relations between measures of HRV (CSI, CVI and RMSSD) and executive functioning (performance speed and accuracy, cue-P3, target-N2 and target-P3).

Finally, a data-driven exploratory approach was used to analyse if clinical symptomatology was associated with specific profiles of autonomic arousal, alertness/vigilance and executive functioning measures. Since this question was predominantly addressed through an exploratory and descriptive approach, we did not have any predictions. However, we expected that children displaying more evident indices of dysregulated arousal (either hypo- or hyper-arousal) would show a profile characterised by more complex symptomatology (e.g., more severe comorbid symptoms, besides ADHD and ASD) and increasingly atypical electrophysiological and behavioural indices of attention and executive functioning.

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Table 5. Summary of the hypotheses of the present study

Measure Task Task-related effects ADHD ASD ADHD+ASD

CSI POP task Reduced during task vs

breaks

Reduced Increased Interactive or additive effects?

CVI POP task Increased during task vs breaks

-- Reduced Like ASD-only

RMSSD POP task Increased during task vs breaks

-- Reduced Like ASD-only

CSI Oddball task Increased during task vs resting

Reduced Increased Interactive or additive effects?

CVI Oddball task Increased in block 2 vs block 1

-- Reduced Like ASD-only

RMSSD Oddball task Increased in block 2 vs block 1

-- Reduced Like ASD-only

P3a Oddball task Increased for deviant vs standard tones

Reduced amplitude Delayed latency

-- Like ADHD-only

MMN Oddball task Increased for social vs non- social stimuli

-- Reduced amplitude Like ASD-only Absolute/Relative

alpha power (during breaks, pre-cue and post- cue temporal periods)

POP task Increased during the POP task, compared to the breaks (pre-cue > post-cue)

Increased post-cue Generally reduced Interactive or additive effects?

Slope of change in baseline Pupil Size

Gap-overlap task Within-block negative slope Reduced negative slope -- Like ADHD-only Slope of change in SRTs

Gap-overlap task Within-block positive slope Increased positive slope

-- Like ADHD-only

Intra-individual variability of SRTs

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Measure Task Task-related effects ADHD ASD ADHD+ASD

Intra-individual variability of RTs

POP task Increased RTV -- Like ADHD-only

SRTs Gap-overlap task Faster SRTs in baseline vs overlap trials;

Faster SRTs for social vs non-social stimuli; Faster SRTs for social vs non-social stimuli, in overlap trials;

Faster SRTs for dynamic vs static trials Slower SRTs in overlap trials; Slower SRTs in overlap trials; Slower SRTs to orient to social stimuli, especially in overlap trials; Slower SRTs in dynamic trials. Additive effects RTs (correct response)

POP task Increased for high- vs low- demands trials Slower RTs, especially in high- demands trials Slower RTs, especially in high- demands trials

Interactive effect (slower RTs than ADHD-only and ASD-only)

% of correct responses

POP task Reduced, especially

in high-demand trials

Reduced,

especially in high- demand trials

Interactive effect (reduced % than ADHD-only and ASD-only)

Cue-P3 POP task Increased amplitude for high- vs low-demands trials

Reduced amplitude, especially during high-demand trials

-- Like ADHD-only

Target-N2 POP task Increased amplitude for high- vs low-demands trials

Reduced amplitude Delayed latency

Reduced amplitude

Interactive effect (reduced amplitude than ADHD- only and ASD-only) Target-P3 POP task Increased amplitude for

high- vs low-demands trials

Reduced amplitude Delayed latency

Reduced amplitude ‘--’ indicates that no effect of ADHD or ASD was predicted for that specific measure